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Construct a triangle ABC with side BC = 7 cm,  \angle B=45^{\circ},\angle A=105^{\circ}. Then construct another triangle whose sides are  \frac{3}{4} times the corresponding sides of the  \bigtriangleup ABC.

 

 

 

 
 
 
 
 

Answers (1)

Given : In  \bigtriangleup ABC

BC=7\; cm

\angle B=45^{\circ}

\angle A=105^{\circ}

\angle A+\angle B+\angle C=180^{\circ}

\Rightarrow 105^{\circ}+45^{\circ}+\angle C=180^{\circ}

\Rightarrow \angle C=30^{\circ}

Steps for construction :

(i) Draw a line BC of 7 cm.

(ii) Draw  \angle B=45^{\circ}  and  \angle C=30^{\circ}

(iii) Let point A be the point where rays from B and C intersect.

(iv)  \bigtriangleup ABC  is the required triangle.

(v) Now take scale factor  \frac{3}{4}<1.

(vi) Make a ray BX making acute angle with BC.

(vii) Mark 4 points  (B_1,B_2,B_3,B_4)  on BX such that  BB_1=B_1B_2=B_2B_3=B_3B_4.

(viii) Join  B_4C.

(ix) Draw a line parallel to  B_4C  from point B_3  intersecting BC at C'. Join  B_3C'.

(x) Draw a parallel line  (A'C')  to AC intersecting at A'

(xi)  \bigtriangleup A'BC'  is formed which  \frac{3}{4}\bigtriangleup ABC.

 

Posted by

Ravindra Pindel

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